The present invention relates to methods for fabricating optical assemblies for optical recording heads, and more particularly to a method for fabricating optical assemblies for flying heads having solid immersion lenses.
Optical data storage systems are of great commercial and academic interest because of their potential for very high data density. In magnetic recording, the data density may be limited by particle size. In optical recording, the data density is often only limited by the diffraction limit of the illuminating light. In practice, the data density is in part also limited by the minimum diameter illuminating radiation such as a laser beam that can be focussed on the disk.
To reduce the laser spot diameter, several methods can be employed. Higher frequency light may help matters because it has a smaller wavelength. Increasing the numerical aperture of the lens may also help to decrease spot size.
One way of improving resolution is to use a solid immersion lens (SIL). These lenses, among other advantages, partially avoid diffraction effects, thus allowing higher data densities.
An object of the invention is to provide a method of fabricating an optical assembly in which a SIL is fabricated or installed for optimum data densities.
Another object of the present invention is to fabricate a slider system for a flying head having an objective lens and SIL which are in focus without the need for automatic focusing.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combination particularly pointed out in the claims.
In one aspect, the present invention is directed to a method of manufacturing an optical assembly in a mold. A first step locates a substrate in the mold. The substratexe2x80x94may have a first opening adjacent the top of the substrate, a second opening adjacent the bottom of the substrate, and a volume between the first and second openings which is substantially empty. The first opening may have a radius greater than the second opening and the first and second openings may be substantially concentric. Another step may be injecting a transparent material into a volume between the first and second openings such that a solid immersion lens is formed when the material hardens.
Implementations of the method may include the following features. A magnetic coil may be located on the substrate substantially concentric with and adjacent to the second opening. The material may be injected through the second opening.
In another aspect, the invention is directed to a method of manufacturing an optical assembly. A first step is forming a solid immersion lens. Another step may be placing a solid immersion lens into a tapered hole located between a first and a second opening in a substrate.
In a further aspect, the invention is directed to a method of fabricating an optical assembly, including the steps of forming a tapered hole in a substrate, forming a solid immersion lens having a tapered portion, and placing the tapered portion of the solid immersion lens into the tapered hole in the substrate.
In a further aspect, the invention is directed to a method of fabricating an optical assembly in a mold, including a first step of locating a substrate in a mold. The substrate may have a first opening adjacent the top of the substrate, a second opening adjacent the bottom of the substrate, a volume between the first and second openings and a magnetic coil substantially concentric with and adjacent to the second opening. The first opening may have a radius greater than the second opening and the first and second openings may be substantially concentric. Other steps may include locating a partial solid immersion lens on the top of the substrate adjacent and overlapping the first opening, and injecting a transparent material into a volume between the first and second openings so that the partial solid immersion lens and the injected material together form a solid immersion lens.
In a further aspect, the invention is directed to a method of manufacturing an optical assembly. The method includes steps of forming a solid immersion lens having a curved surface and a flat portion; forming, placing or shaping a mesa on the flat portion of the solid immersion lens; and placing the solid immersion lens into a hole in a substrate.
Implementations of the invention include the following features. A thin film magneto-optic coil may be deposited adjacent to and encircling the mesa. The mesa may be formed, for example, by grinding the flat portion of the solid immersion lens, chemically etching the flat portion of the solid immersion lens, or depositing the mesa through a mask.
In a further aspect, the invention is directed to a method of manufacturing an optical assembly. The method includes the steps of forming a tapered solid immersion lens having a spherical portion and a flat mesa portion and placing the tapered solid immersion lens into a tapered hole in a substrate.
In a further aspect, the invention is directed to a method of manufacturing an optical assembly. The method includes the steps of forming a solid immersion lens having a spherical portion and a flat portion, placing the solid immersion lens into a hole in a substrate, forming a mesa on the flat portion of the solid immersion lens, forming a separate thin film having a hole therethrough, fabricating a magnetic coil on the thin film, such that the center of the coil is near the center of the hole, and mounting the thin film on the substrate such that the mesa at least partially protrudes through the hole and magnetic coil. In an implementation of the method, the thin film may be silicon nitride (SiN).
In a further implementation, the invention is directed to mounting a substrate and optical assembly in a slider having an air bearing surface and a top surface such that the flat portion of the solid immersion lens is approximately co-planar with the air bearing surface. An objective lens may be placed on or near the top surface of the slider. In this way, the slider, the objective lens, and the solid immersion lens maintain fixed distances from each other.
In a further implementation, the slider or the solid immersion lens may be lapped such that the mesa of the solid immersion lens is approximately co-planar with the air-bearing surface of the slider.
In a further aspect, the invention is directed to a method of integrating an optical assembly into a slider. The method includes the steps of forming a substantially transparent slider having a void in a top surface thereof, installing a partial solid immersion lens into the void, placing an objective lens on or near the top surface of the slider, and forming a mesa that extends from a bottom surface of the slider. The slider, the partial solid immersion lens, the objective lens, and the mesa may maintain a fixed relationship with respect to each other.
In a further aspect, the invention is directed to a method of integrating an optical assembly into a slider. The method includes steps of forming a substantially transparent slider having a partial solid immersion lens formed therein, placing an objective lens on or near the top surface of the slider, and forming a mesa that extends from a bottom surface of the slider.
In a further aspect, the invention is directed to a method of integrating an optical assembly into a slider. The method includes steps of forming a substantially transparent slider having a void in a top surface thereof, installing a partial solid immersion lens into the void, placing an objective lens on or near the top surface of the slider, placing a glass plate on a bottom surface of the slider, and forming a mesa that extends from the glass plate. The slider, the partial solid immersion lens, the objective lens, the glass plate, and the mesa maintain a fixed relationship with respect to each other.
In a further aspect, the invention is directed to a method of integrating an optical assembly into a slider. The method includes the steps of forming a substantially transparent slider having a partial solid immersion lens formed therein, placing an objective lens on or near a top surface of the slider, placing a glass plate on a bottom surface of the slider, and forming a mesa that extends from the glass plate.
Implementations of the above aspects include the following features. A coil may be mounted adjacent the mesa. The coil may encircle the mesa.
The solid immersion lens may be formed by grinding, machining, lapping, or molding. The solid immersion lens may have a conical or pyramidal portion.
The injected material may be, for example, liquid glass or plastic with an index of refraction approximately equal to the index of refraction of the partial solid immersion lens.
Advantages of the invention include the following. An optical assembly having a SIL for high data densities may be manufactured in a simple fashion. The fabrication technique allows the optical components to maintain a fixed focus, eliminating the need for an active focussing mechanism.